So I was looking for the Service Mode in the nightly mame_libretro.dll and founds out it hiding by the name of Diagnostics.
You’ll find it in the RGUI (F1 shortcut) > Core Options
Enable the Diagnostics option and the Service Mode should popup right after you escape the RGUI (ESC. key). If it doesn’t show, try to disable it, escape the RGUI, re-open the RGUI and re-enable the Diagnostics.
Works great with CPS1, 2 and 3.
Then I tried access the Service Mode in fb_alpha_libretro.dll because I like to play Metal Slug with the blood red and because I can’t make the mame_libretro.dll work with Neo Geo roms.
And it’s tricky because you have to enable the UniBios in the Core Menu.
You’ll find it in the RGUI (F1 shortcut) > Core Options
Enable the UniBios option, escape the RGUI, and reset the Game (H key). The game should now boot with the UniBios.
If not, keep the UniBios enable, quit and restart the Game.
From there you have 2 options :
Hold down the buttons 1, 2, 3 and you can now change the region for the game and setup for arcade or console mode.
Hold down the buttons 2, 3, 4 and you have access to the Service Mode.
The tricky part it’s that the Core doesn’t save your settings. You’re good to restart the process each time you change the game.
So if anyone knows how to access the fb_alpha_libretro.dll Service Mode without activating the UniBios or have a way to save the settings, I’d like to know ! 